Afshin Partovi
Volume 2, Issue 4 , January 2011, Pages 187-196
Abstract
Remotely sensed data is now being acquired and it is hoped the earth’s surface will be imaged more and more precisely to support their information systems by accurate data with high spatial resolution. The most advantage of this technique can be mentioned to acquire earth surface data with all ...
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Remotely sensed data is now being acquired and it is hoped the earth’s surface will be imaged more and more precisely to support their information systems by accurate data with high spatial resolution. The most advantage of this technique can be mentioned to acquire earth surface data with all of its details depend on the spatial resolution of satellite imagery. Due to remote sensing applications, there are some factors with efficient effects on the accuracy of the obtained results. Such that, there is not avoidable Relief Displacement correction in DEM generation or data fusion works. A lot of researches have been done to remove Relief Displacement caused by imaged feature’s height and scanning array by different algorithms of Ortho Photo rectification. In this approach the geometry of 1A and 1B level products of ASTER images was studied to develop a method based on rotation re sampling for Epipolar Stereo Pair Model generation in Non-Photogrametric software. Then the generated model was used to digitize contour lines with 100 meters interval of constant parallax (in row-parallax on the screen, i.e. col= 0). The result of comparison shows a consistent shift in georeference of digitized contour map with respect to the existing contour map and ground control points that can be caused by the effect of side ward looking angle and height of feature. Thus, the effective parameters such as pointing angle and height of feature were applied to develop a mathematical formula in Excel software to measure amount of shifts and finally correct it. The research show the amounts of shift are varying depends on position of the points in the image and its heights. Furthermore, the developed formula enables us to remove Relief Displacement without any changes on the radiometric properties of image data.
Seyed Mahmoud Reza Tabatabaei; Mohammad Roghani
Volume 2, Issue 4 , January 2011, Pages 197-205
Abstract
In calculation of catchments time of concentration, TC, lump equations are often used. Therefore, TC is not accessible for different parts of the catchments. In this research, using object oriented programming in the GIS environment a fully distributed model has been designed and developed. The model ...
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In calculation of catchments time of concentration, TC, lump equations are often used. Therefore, TC is not accessible for different parts of the catchments. In this research, using object oriented programming in the GIS environment a fully distributed model has been designed and developed. The model is able to calculate the time of concentration for any parts of the catchment to its outlet in a raster map. Model input layers are DEM, rainfall intensity, Manning’s roughness coefficient and catchment stream network. The most important outputs of the model are slope, flow direction and flow accumulation layers and isochronal surfaces. In the presented model, catchment cells are divided into two basic classes including channel cells and overland flow cells. Kirpitch and Kinematic wave equations have been used to calculate the time of concentration for the channel and overland flow cells respectively. In addition, rainfall-runoff hydrologic software, RAFTS-XP, has been used to evaluate the accuracy of TC model results. The result of TC model shows that calculated travel time had suitable synchronization to real time, which has been estimated using observed events and the calibration of RAFTS-XP. Considering the point that catchment response for all events which used by RAFTS-XP is based on different rainfall intensities with identical time of concentration, so observing different behaviors in flood hydrographs seems reasonable.
Masoud Sajedi Sabegh; Mojtaba Saneie; Mehdi Habibi; Ali Akbar Abbasi; Mehdi Ghadimkhani
Volume 2, Issue 4 , January 2011, Pages 206-210
Abstract
In this paper the effect of tree planting in a river bank on the shear velocity of flow was studied in a laboratory environment. At first a physical model was established in a 1.5m wide, 30m long experimental flume with a longitudinal slope of 0.01. Then a number of bars with 6.5mm in diameter, ...
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In this paper the effect of tree planting in a river bank on the shear velocity of flow was studied in a laboratory environment. At first a physical model was established in a 1.5m wide, 30m long experimental flume with a longitudinal slope of 0.01. Then a number of bars with 6.5mm in diameter, stimulated as trees, were located on the bank surface with a slope of 1:3 in two different orientations (square and triangular forms), three different heights (5, 6.5 and 8cm), and three different intensities (6*6/6*3, 8*8/8*4, 10*10/10*5). After that, the flow hydraulic parameters (such as discharge, water level and velocity) and their variation versus the change in experimentally planted trees were measured and analyzed. At least 19 series of laboratory tests with 5 different discharges were implemented. The results showed that, there is a relationship between planted tree and shear velocity. Also relationship between shear Reynolds () and the average velocity to shear velocity ratio () showed that vegetation could increase the roughness coefficient also by increasing the tree density, the ratio of and the roughness are increased. The roughness coefficient in all cases of not using vegetation, tree planted in square form and tree planted in triangular form, was increased respectively.
Hamid Reza Matinfar; Fereydoun Sarmadian; Seyed Kazem Alavipanah
Volume 2, Issue 4 , January 2011, Pages 211-220
Abstract
Soil salinity is one of the main increasing problems of the world. In the recent years application of remote sensing and GIS techniques in order to assess saline soils is used because they bring about vast uniform coverage of ground phenomena in a short time. The images of LISS III sensor of the Indian ...
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Soil salinity is one of the main increasing problems of the world. In the recent years application of remote sensing and GIS techniques in order to assess saline soils is used because they bring about vast uniform coverage of ground phenomena in a short time. The images of LISS III sensor of the Indian satellite (IRS) were used in this research. The Brightness index (BI) could discriminate highly saline soils from non –saline and the salinity index (SI) show high potential to separate very high, high and non- saline soils. Results of supervised classification without combination DEM and remote sensing data have overall accuracy of 76%, producer accuracy of 78% and user's accuracy of 82%. While in supervised classification combination of remotely sensed data and DEM have overall accuracy of 98.1% , producer accuracy of 98.28% and user's accuracy of 98.4% .The reason for low accuracy of the classification , before combination of remote sensing and topographic data , can be explained by highly moist saline soils spectral interference with non-saline soils (soil with 25 to 65% gravels) , but these two soils had different topographic condition with 200 meters elevation difference , thus , with combination of the DEM , this kind of area and other areas with similar conditions have been separated from each other.
Behzad Raighani; Said Soltani Koopani; Seyed Jamaleddin Khajeddin; Sousan Barati
Volume 2, Issue 4 , January 2011, Pages 221-236
Abstract
Snow-cover and its equivalent water, supply 1/3 of the water requirements for farming and land irrigation throughout the world. Therefore, water contents estimation of a snow-cover or estimation of snowmelt runoff is necessary for hydrologists. Several snowmelt-forecasting models have been suggested ...
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Snow-cover and its equivalent water, supply 1/3 of the water requirements for farming and land irrigation throughout the world. Therefore, water contents estimation of a snow-cover or estimation of snowmelt runoff is necessary for hydrologists. Several snowmelt-forecasting models have been suggested which most of them require continuous monitoring of snow-cover. The most efficient means of monitoring snow-cover patches are remote monitoring through satellites imagery. In this research, snowmelt runoff forecasted in a new scheme, using maximum and mean daily temperatures, two snowmelt measuring device and MODIS data. According to the outcome results, one can map snow-covered area with sufficient precision using MODIS data, while the map is useful for related calculations about snow patches. We calculated, after studying the satellite images, the snow-cover changes predicted in a new way for the periods that the MODIS data was not available. Maps were produced and with control of ground truthing their very high precisions confirmed. The melted water resulted from temperature changes were modeled as equations, which, their calculated amounts are comparable to the ground truthing points very well. With regards of water flow changes, equations calculated to estimate the daily melted water flow. These equations are comparable to the ground truthing points as well.
Majid Heidarzadeh; Seyed Said Moosavi nadooshani; Azadeh Mahdipoor
Volume 2, Issue 4 , January 2011, Pages 237-249
Abstract
In water resources projects, the maximum instantaneous discharge as well as the maximum average flood discharge and their corresponding volumes in any given durations and return periods are required. In this study a method selected to investigate the Partial Duration Series (PDS) where the sample sizes ...
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In water resources projects, the maximum instantaneous discharge as well as the maximum average flood discharge and their corresponding volumes in any given durations and return periods are required. In this study a method selected to investigate the Partial Duration Series (PDS) where the sample sizes are greater than pre-identified thresholds. In this method, randomly several observations are selected for a given year while some years have no observation greater than the threshold.. Selecting the most appropriate observations as representative for floods is the main characteristic of the PDS method. In contrast, the main advantage of the Maximum Annual Series (MAS) can be referred to the inherent independence of the data. This subject can be validated and examined in the PDS using randomness and stationary tests. The Soltani hydrometric station in Halilrood River located in south-west of Kerman province, Iran was selected as a case study. Comparison of the theoretical results of the PDS and MAS methods indicated that the estimated values of PDS for 10 years and smaller return period are greater than those of MAS. However the results for this study area show this difference is negligible for 27 years data. The PDS method quickly approaches the population for a given data. Therefore the PDS is favorable for hydrometric stations with limited data availability. The required software coherent with Iranian data were prepared and presented in this study.
Younes Daghigh; Ali Toloueiyan
Volume 2, Issue 4 , January 2011, Pages 250-256
Abstract
One of the subjects that should be considered in coastal dykes design is interaction of saltwater and freshwater in the body and under the dykes. This paper evaluates the effect of clayey blanket and vertical cutoff on freshwater and saltwater interaction in the body and under the dyke by using ...
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One of the subjects that should be considered in coastal dykes design is interaction of saltwater and freshwater in the body and under the dykes. This paper evaluates the effect of clayey blanket and vertical cutoff on freshwater and saltwater interaction in the body and under the dyke by using CTRAN/W finite elements model. This model has developed during 2001 at Alberta Canada for studying on movement of contaminants such as salt and polluter particles through porous materials. In this study, five analyses group have been performed. First group was studying on status of salt invasion promotion after the dyke constructing and before filling from river water. Second group was after filling of dyke side to 3.5 meters height. Third group analysis was the same as second group but using clayey blanket instead. Fourth group was analysis was the same as second group but using vertical cutoff instead, and fifth group was using conjointly clayey blanket and vertical cutoff. The study shows that: using clayey blanket, the maximum leaching speed occurred after 5 days, while after 10 days, it remains constant. Also conjunctive use of clayey blanket with vertical cutoff had the maximum effect on prevention of soil salinity.
